Oil burner and means of controlling the combustion of fuel oil therein



Dec. 13, 1960 P. AYASSE ,101

OIL BURNER AND MEANS OF CONTROLLING THE COMBUSTION OF FUEL OIL THEREINFiled June 5, 1958 2 Sheets-Sheet 1 4 K "35 i Z IL) 0 3g 4 43 I T 4 34.34

56 37 y 4 i 46 o Z3 24 2 s r 4 4 Fly,

INVENTOR.

' PAUL AmssE av A Arr-049M675 Dec. 13, 1960 SSE 2,964,101

P. AYA OIL BURNER AND MEANS OF CONTROLLING THE COMBUSTION OF FUEL OILTHEREIN Filed June 5, 1958 2 Sheets-Sheet 2 INVENTOR. P Il/L 47H 5 5EMaw; Z'M'n ATTORNEYS United States Etent-C (lIL BURNER AND MEANS OFCONTROLLING THE COMBUSTION F FUEL OIL THEREIN Paul Ayasse, ObereBergstrasse 2, Oberachern, Baden, Germany Filed June 5, 1958, Ser. No.740,106

Claims priority, application Germany June 12, 1957 Claims. (Cl. 158-5)The present invention relates to devices for improving the combustion offuel oil in general, and in particular to an improved oil stove and anoil burner. More particularly, this invention relates to a means forimproving the combustion of fuel oil in which the oil is supplied to theburner of an oil stove drop-by-drop and is then vaporized prior to theactual combustion process within a closed heated chamber, which isprovided with outlet openings facing toward the combustion chamber ofthe oil stove, whereupon the vaporized oil is mixed within thecombustion chamber with combustion air to form a combustible fuelmixture.

- In order to attain a combustion of fuel oil of adequate efliciency itis primarily necessary to supply the oil vapor with a suflicient amountof oxygen. For producing a combustible mixture of oil vapor and air, oneor the other of two different means are generally applied, namely,vaporization or atomization. While the latter means is only used for theoperation of larger heating plants, the former is preferable for smallerfurnaces, particularly smaller stoves or similar heaters.

In vaporizing the fuel oil it has been customary to use a bowl-shapedretort, the bottom of which was heated by means of a wick or the like soas to heat and gradually evaporate the oil within the bowl and coveringthe entire surface of the bottom thereof. This oil vapor combines withthe air surrounding the burner to form a moist fuel mixture. Such amoist mixture of oil vapor and air has, however, the disadvantage thatwhen burning it will produce a very large quantity of soot and smoke.

For shielding the fuel oil Within the burner bowl from the flames in thecombustion chamber, it has already been proposed to vaporize the oilwithin a closed heated chamber which is provided with relatively largeoutlet openings through which the oil vapor then passes into the actualcombustion chamber. However, it has been found that, if primary airpasses through the outlet openings into the closed vaporizing chamber,the flames within the combustion chamber will easily flash back into thevaporizing chamber and ignite the mixture of oil vapor and air therein.

7 It is the principal object of the present invention to provide meansfor increasing the efliciency of an oil stove and the oil burner thereinby vaporizing the fuel oil within a closed chamber as intensely andthoroughly as possible so as to form a dry oil vapor and also preventthe flames within the combustion chamber of the stove from flashing backinto the closed vaporizing chamber.

for attaining the above-mentioned object, the present 65 inventionprovides suitable means for conducting the oil vapor which rises fromthe bottom of the vaporizing chamber so as to pass along suitableheating surface which increase the temperature of the oil vapor and atthe same time produce a pressure head-within the vaporizing chamber.

Such additional heating of therising oil vapor results Patented Dec. 13,1960 2 in a very thorough, intensive and dry vaporization of the fueloil which, in turn, results in a very thorough combustion and thus in amuch higher heating efficiency than was attainable in previous oilburners of this type.

Another important advantage attained by the present invention is thefact that the tarry oil residues commonly occurring in all bowl type oilburners will be totally avoided. Furthermore, while in previous oilburners of this type the preliminary treatment of the fuel oil as wellas its combustion was usually accompanied by considerable noise,according to the present invention this will be accomplished absolutelysilently. Another great advantage of the invention is that, while thestarting of previous burners required a considerable length of time andas much as 30 to minutes, the starting of a burner according to theinvention requires no more than about 5 or 6 minutes. Finally, thepressure head produced according to the invention within the vaporizing.chamber also effectively prevents any entry of primary air into suchchamber, and it thus prevents the flames within the combustion chamberfrom flashing back intothe vaporizing chamber.

The invention is preferably carried out by employing an oil burner whichis provided with a closed heatable vaporizing chamber into which the endof the oil feed line extends and which has outlet openings facing towardthe combustion chamber through which the oil vapor may enter into thelatter. Behind this vaporizing; chamber, the oil burner is provided withan ignition devicewhich extends into the combustion chamber and therein;ignites the oil vapor after it has been mixed with combustion air.According to the invention, the outlet openings of the vaporizingchamber from which the oil vapor is discharged into the combustionchamber are provided;- within the upper part of the vaporizing chamber,while" the heating surfaces which produce the pressure head within thevaporizing chamber are provided between these outlet openings of the oilvapor and the bottom of thevaporizing chamber.

The mentioned heating surfaces may be further supplemented either byseveral horizontally mounted platesor the like following each otherwithin the vaporizing chamber which are provided with openings orpassages for the oil vapors or by at least one layer of heat-com;ductive material, for example, steel wool, within the" vaporizingchamber, which allows the oil vapors to pass therethrough. If theheating surfaces consist, for example, of two horizontal plates spacedabove each other and extending almost across the entire cross-sectionalarea of the-vaporizing chamber, the passages for the oil vapor in thelower plate facing toward the bottom of the vaporizing chamber arepreferably disposed at one side of the chamber, while the passages inthe upper plate facing toward the upper end of the chamber are disposedat the other side so that the oil vapor will flow through the vaporizingchamber not only in a vertical direction but also in a horizontaldirection. If the passages in these plates are thus disposed, it isadvisable to provide the outlet openings from the vaporizing chamberwithin the upper part thereof and at the same side where the passagesare pro-' vided in the lower plate facing toward the bottom of thechamber so that, when the oil vapor flows through the passages in theupper plate, it has to flow oncemore in the horizontal direction throughthe upper part of the vaporizing chamber before .itcan leavefthis'chamber" and pass through the outlet openings into the combustion ingsfor the oil vapor are provided at the outer upper'ed g Ca 2,964,10l

of such casing, while the central opening thereof serves as a passagethrough which the combustion air is drawn through the base of the burnerinto the combustion chamof the oil feed pipe which projects from belowinto the central opening of the annular vaporizing chamber with at leastone oil intake pipe which extends into such chamber and is disposedtherein between the bottom of that chamber and the lower heat-conductingplate therein. If several such oil intake pipes are provided on theupper end of the main oil feed pipe the free ends of these intake pipesare preferably uniformly distributed within the annular vaporizingchamber near the bottom thereof, for example, in a star-shapedformation.

This particular design and arrangement of the end of the oil feed pipeprojecting into the central opening of the annular vaporizing chamberhas the advantage that the fuel oil supplied through the feed pipe willbe cooled by the ascending combustion air which passes uniformly alongthe outside of the feed pipe before entering into the combustion chamberof the stove whereby the fuel oil will be prevented from vaporizingprematurely, that is, within the feed line. For this reason, it is alsoadvisable to make the end of the feed pipe of a material which has a lowthermal conductivity.

For insuring that the fuel oil supplied through the feed pipe will beuniformly distributed to the oil inlet pipes leading into the vaporizingchamber, and for preventing the fuel 'oil from flowing into this chambertoo quickly, the end of the feed pipe is preferably provided with anozzlelike constriction from which the oil will then fiow into theslightly downwardly inclined intake pipes and pass drop-by-drop into thevaporizing chamber.

Another advantageous feature of the present invention consists inmounting a cylinder or the like which is closed at its upper end at apoint above the central opening of the annular vaporizing chamber andcoaxially therewith so as to cover the opening. The side wall of thiscylinder is provided with a plurality of uniformly distributed outletopenings through which the combustion air which is drawn through thecentral opening in the vaporizing chamber can pass into the combustionchamber. The outer diameter of this cylinder is preferably made smallerthan the diameter of the ring of outlet openings for the oil vapor whichare provided along the outer upper edge of the vaporizing chamber, sothat the oil vapor will rise laterally along the cylinder and will mixwith the combustion air emerging from the outlet openings in the sidewall of the cylinder to form a combustible mixture.

This cylinder which uniformly distributes the combustion air within thecombustion chamber has preferably mounted thereon a tube of a smallerdiameter than the cylinder and extending coaxially thereto. This tube isclosed at its upper end and the side wall thereof is likewise providedwith a large number of uniformly distributed air outlet openings. Byproviding such additional perforated tube on the air-distributingcylinder, it is possible first to supply the oil vapor emerging from thevaporizing chamber with primary air which combines with the oil vaporinto a combustible mixture, and then to supply such mixture through theoutlet openings in the wall of the tube with additional secondary air.

The cylinder is provided with a plurality of radially projecting hollowribs which are uniformly distributed along the side wall of the cylinderand communicate with the inside thereof. Each of these ribs is providedwith at least two air outlet openings which extend in a tangentialdirection and are disposed above each other for conducting the primarycombustion air which has passed through the cylinder and the ribs insuch tangential direction into the oil vapor within the combustionchamber so as to intermix and thoroughly combine the oil vapor with thecombustion air. I

The combustion air and the oil vapor may be still more intimately mixedby providing suitable guide surfaces on the outer edges of the hollowribs. The'se guide surfaces should extend in a peripheral direction atleast along the area of the ribs in which the air-outlet openings arelocated. The ribs themselves should furthermore be inclined at an angleof about 20 to 25 to the vertical plane. The combustion air will thenemerge from the ribs in a downwardly inclined direction, and, aftermixing with the oil vapor, ascend in a spirally curved direction.

If, after starting the operation of the burner for only a short time,the heating unit should be switched off to reduce the consumption ofelectric current, it will be necessary to generate the heat, which isrequired to continue the vaporization of the fuel oil, by carrying out apart of the combustion at a point closely adjacent to the vaporizingchamber. The outer wall of the vaporizing chamber is for this purposeprovided with additional oilvapor outlet openings at a point directlyunderneath the cover plate of the chamber and extending in atangentially inclined direction. The oil vapor, after being producedwithin the vaporizing chamber, will then be discharged therefrom throughthese additional tangential outlet openings and after being mixed withprimary combustion air, it will burn up directly adjacent to thevaporizing chamber and thereby heat the latter. The most effectivemanner of supplying the primary air will in this case be attained byextending the hollow ribs downwardly along the outer wall of thevaporizing chamber and spaced at a small distance therefrom so that,when the combustion air is discharged from the downwardly projectingends of the ribs through additional, tangentially inclined outletopenings in these lower ends of the ribs, it will impinge directly andat an angle upon the oil vapor which emerges laterally from thevaporizing chamber. Thus, the oil vapor will combine very intimatelywith the combustion air and form an easily combustible fuel mixture.

In order to insure that the combustion of the oil vapor emerging fromthe lateral outlet openings of the vaporizing chamber will occur at anarea as closely as possible to the outer side wall of the vaporizingchamber and preferably directly adjacent thereto, additional guide.surfaces are provided between the air outlet openings in the upper partof the ribs and the additional outlet openings in the lower ends of theribs. These guide surfaces extend at right angles to the ribs andconnect each rib with the adjacent rib. If the ribs themselves areinclined as above described, these guide surfaces will then also beinclined relative to the horizontal plane so that the combustion gaseswill at first be deflected in the downward direction.

For preventing the combustion gases from rising too quickly within thecombustion chamber, the perforated pipe socket which is mounted on theair-distributing cylinder is preferably provided with one or morelaterally projecting guide surfaces at a point above its air outletopenings. These guide surfaces retard the ascent of the combustion gaseswithin the combustion chamber by deflecting the same. Additional guidesurfaces may also be mounted on the inner wall of the combustion chamberwhich cooperate with the guide surfaces on the tube by forming anintermediate throttling passagefor the combustion gases. Above theseguide surfaces,

the side wall of the upper closed end of the tube be provided withadditional air outlet openings through which any possible components ofthe mixture of oil vapor and air which have not as yet been completelycombusted below these guide surfaces will be supplied with additionalcombustion air.

The ignition unit is mounted at a point above the outlet openings forthe oil vapor, and preferably at the level in which the air-outletopenings in the pipe socket are located. It may be secured either on theside wall of the combustion chamber or on the tube. In the latter case,the lead-in wires for the electric ignition coil may be passed throughthe central opening in the vaporizing chamber and through the inside ofthe cylinder and the tube thereon.

The oil burner according to the invention is preferably used in an oilstove which includes an oil tank, which is connected by a feed pipe tothe burner, and has a combustion chamber therein which may be connectedto a chimney or the like. The oil burner may in that case be mounted ona horizonotal base plate which closes the entire lower end of thecombustion chamber and has an opening therein which coincides with thecentral opening of the annular vaporizing chamber of the oil burner sothat the combustion air can flow from below into and through the burnerand thus into the combustion chamber of the stove. If the combustionchamber is of a cylindrical shape, the inner wall thereof will be heatedvery uniformly by the flames which are directed substantially radiallytoward this wall.

In comparison with a coal stove which generally can only be very roughlycontrolled by a variation in the supply of combustion air, an oil stoveif properly equipped will allow a much more accurate control of thecombustion process, and thus a much more efficient operation of thestove itself and a much better utiliza tion of the heat energy containedin the fuel. For attaining such accurate control and for realizing theadvantages thereof to the fullest extent which was then possible,previous oil stoves of modern design were ent types. I

,Further objects, features, and advantages of the present invention willbe apparent from the following detailed description thereof,particularly when read with reference to the accompanying drawings, inwhich 'Fig. 1 shows a vertical cross section of the oil burner accordingto the invention;

'Fig. 2 shows a cross section taken along line 22 of Fig. 1;

Fig. 3 shows a perspective view of the same oil burner. Referring to thedrawings, the oil burner according to the invention has an annularvaporizing chamber 2 of a substantially rectangular cross-sectionalshape which is, secured to an annular base plate 1 and has a centralopening 3. Directly underneath the bottom 4 of vaporizing chamber 2,which forms an annular bowl and is adapted to receive the fuel oil forvaporization therefrom, suitable heating means 5 are provided whichpreferablyconsist of a plurality of heating coils which are connectedinparallel, for example, of one heating coil of about 100 watts and asecond coil of about 300 watts.

As illustrated particularly in Fig. 2, the upper cover plate 6 ofvaporizing chamber 2 is provided near the outer edge thereof with a ringof outlet openings 7 through .Which the oil vapor which has beenproduced in chamber 2 passes into the combustion chamber.

.The fuel oil is supplied through a feed pipe 8, the upper end 9 ofwhich projects from below into the central opening 3 of the annularvaporizing chamber 2 and preferably carries three oil inlet pipes 11which are disposed at an angle of 120 relative to each other, asillustrated particularly in Fig. 2. These three inlet pipes 11 extendinto vaporizing chamber 2 and terminate directly above its bottom 4. Inorder to attain an oil feed as uniform as possible but of not too greata volume, the upper end 9 of feed pipe 8 is preferably made of anozzlelike shape. Furthermorme, inlet pipes 11 are inclined at such anangle toward the bottom 4- fall upon the bottom 4 of vaporizing chamber2 drop Above the outer ends of inlet pipes 11, vaporizing chamber 2 isprovided internally with a horizontal metal ring 12, the inner edge ofwhich engages directly against the inner wall 13 of chamber 2. This ring12 is made of a width less than that of the bottom 4 so that an annularslot 15 will be formed between its outer edge and the outer wall 14 ofchamber 2. At a suitable distance between the upper cover plate 6 ofchamber 2 and ring 12 a similar metal ring 16 is mounted in a horizontalposition. This ring 12, however, abuts directly against the outer wall14 of chamber 2, and it is made of a width so that another annular slot17 is formed between its inner edge and the inner wall 13 of chamber 2.This staggered arrangement of slots 15 and 17 produces the result thatthe oil vapor which rises from the bottom 4 of vaporizing chamber 2, inpassing to the outlet openings 7 in cover plate 6, must flowhorizontally along i will be formed which prevents any combustion airfrom entering into vaporizing chamber 2. On the other hand, however,rings 12 and 16 will operate as additional heating surfaces and transmitthe heat which they receive 7 from the walls of chamber 2 to the oilvapor as it passes along the same. The vapor will thereby be superheatedand dried, and any incompletely vaporized o-il particles will thereby befully vaporized, so that the dry oil vapor after emerging fromvaporizing chamber 2 and mixing with the combustion air will burn downcompletely.

The upper cover plate 6 of vaporizing chamber 2 fur-' ther carries anannular trough 19 of a U-shaped cross section, the outer wall 21 ofwhich surrounds the outlet openings 7 in the outward direction and theinner wall 22 of which'serves for centering an inverted cup-shapedcylinder 23 which is closed at its upper end and is fitted overvaporizing chamber 2. This cylinder 23 has an outer diameter a asindicated in Fig. l which is smaller than the inner diameter b of thering of outlet openings 7 in the upper cover plate 6 of chamber 2.

As illustrated particularly in Fig. 3, the outer wall 24 of cylinder 23is provided with a plurality of radially projecting ribs 25 which areuniformly distributed along this-wall 24 and the inside of whichcommunicates with the inside of cylinder 23. Each of these ribs 25 isprovided, for example, with three outlet openings 26 which extend in atangential direction and are disposed above each other. The combustionair will thus pass in the direction shown by arrows 27 through thecentral opening 3, cylinder 23, and ribs 25 and will be dischargedtherefrom into the combustion chamber through outlet openings 26. Ribs25 have guide plates 23 on their outer wall which extend in a peripheraldirection and they are also inclined at an angle of about 20 to 25 tothe vertical plane. Through the guiding action of these tangential guideplates 28 and such inclination of ribs 25, the combustion air will passfrom the outlet openings 26 in ribs 25 in a tangential direction asshown by arrows 29, meet and thoroughly intermix with the oil vaporrising from outlet openings 7 in cover plate 6 i Y of vaporizing chamber2, and then rise in the form of a.

combustible fuel mixture spirally upward into the combustion chamberabove cylinder 23 in the direction as shown in Fig. 3 by arrows 32.

. In order to render such mixture of oil vapor and air" still morehighly combustible, secondary air is supplied toward these openings.

\ 7 tube 35. These outlet openings 37 are staggered relative to eachother so-that the lines connecting the openings in the upper rows withthe corresponding openings in the lower rows are disposed at an angle ofabout 10 to 30 to the vertical plane. For separating the air whichpasses through the central opening 3 into primary combustion air whichpasses into the combustion chamber through outlet openings 26 in ribs 25and secondary combustion air which passes into the combustion chamber ata higher level through outlet openings 37 in tube 35, the lower end 38of the latter is funnel-shaped and extends into cylinder 23.

Above these outlet openings 37, tube 35 also carries an outwardlyprojecting ring 39 which may cooperate with a further metal ring 43which concentrically surrounds ring 39 and is mounted on the inner wall41 of combustion chamber 42 for preventing the combustion gases fromrising too quickly. Above this ring 39 tube 35 is provided with anotherring of air outlet openings 44 through which additional combustion airwill be supplied to the combustion gases which have passed upwardlythrough the annular gap between rings 39 and 43 so that any residual oilvapor within these gases which has not as yet been burned up below rings39 and 43 will now be burned up completely.

For igniting the combustible fuel mixture which rises in the directionshown by arrow 32, the invention provides an electric ignition unit 45which extends through the wall of tube 35 directly above cylinder 23.The ignition coil 46 of this unit 45 projects radially beyond the outerwall of cylinder 24. The lead-in wires 47 of ignition coil 46 may extendthrough the central opening 3, cylinder 23, and the lower end of tube35.

As illustrated particularly in Figs. 1 and 2, the outer wall 14 ofvaporizing chamber 2 is further provided at a. point intermediate theupper metal ring 16 and the upper cover plate 6 with additional outletopenings 48 which extend in a tangential direction. These outletopenings 48 are equal in number to the hollow ribs 25 but are laterallydisplaced relative thereto. For supplying combustion :air also directlyto the oil vapor which emerges from these additional outlet openings 48,ribs 25 are extended in the downward direction and each of themisprovided with two additional air outlet openings 49 which are disposedat the same level as the tangentially inclined outlet openings 48 andextend in a direction As illustrated in Fig. 3, the downwardlyprojecting parts of the adjacent ribs 25 are connected by guide plates51 which are mounted between the upper air outlet openings 26 in ribs 25and the additional lower air outlet openings 49. These guide plates -1extend at right angles to the walls of ribs 25 and are thereforelikewise inclined at an angle of 20 to 25 to the horizontal plane. Theyprevent the mixture of oil vapor and air forming underneath these guideplates 51 from rising so that it will burn up directly adjacent to theouter wall 14 of vaporizing chamber 2 and thereby heat the latter.

The operation of the oil burner as illustrated in Figs. 1 to 3 is asfollows:

For starting the operation, it is first necessary to switch on theheating unit 5 so as to heat the bottom 4 of vaporizing chamber 2.Thereupon, fuel from an Oll supply tank (not shown) is supplied throughfeed pipe 8 to the downwardly inclined inlet pipes 11, from which itwill pass drop-by-drop upon the heated bottom 4 of vaporizing chamber 2where it will thus be very quickly vaporized. The oil vapor then flowsin the direction shown by arrow 18 along rings .12 and .16, whereby itis dried by the heat emitted from these rings and any liquid oilparticles which might still be contained therein" will be thoroughlyvaporized before passing out of the vaporizing chamber through the upperoutlet oiienings7 and the lateral outlet openings '48. Outside of thevaporizing chamber 2, the oil vapor will then intermix with the aircontained in the combustion chamber 42 and surrounding the oil burner soas to form a combustible mixture which is then ignited by the ignitioncoil 46.

This initial combustion produces a partial vacuum within the combustionchamber 42 whereby a fresh supply of combustion air will be drawn frombelow into the burner through the central opening 3. This air will flow,on the one hand, as primary air out of the out-let openings 26 and 49 inribs 25 and, on the other hand, as secondary air out of the outletopenings 37 in the outer wall of tube 36, and combine with the oil vaporemerging from vaporizing chamber 2 to form an easily combustible mixturewithin the combustion chamber.

After the oil burner has thus been started for only a short time,vaporizing chamber 2 will have been heated, on the one hand, by heatingunit 5 and, on the other hand, by the initial combustion in itsimmediate vicinity to such a high temperature that the vaporization ofthe newly supplied fuel oil will considerably accelerate. This will alsoconsiderably increase the volume of oil vapor emerging from outletopenings 7 in cover plate 6 of vaporizing chamber 2 so that the primaryair supplied through ribs 25 in the direction shown by arrows 27 and 29will be just sufficient to form a combustible fuel mixture which risesupwardly in the direction shown by arrows 32 and will only burn up abovecylinder 23 after the secondary air has been passed into this mixturethrough out-let openings 37 in tube 36 in the direction shown by arrows34. Since the metal ring 39 on the upper part of tube 35 prevents thecombustion gases from rising too quickly, those gases passing to thearea around this upper part will only contain relatively few uncombustedcomponents which will then burn up almost completely after additionalcombustion air has been supplied thereto through the outlet openings 44in tube 36 above ring 39.

Since the oil vapor issuing from outlet openings 48 in the outer wall 14of vaporizing chamber 2 and after the necessary combustion air has beenadded thereto through the lower outlet openings 49 in ribs 25 will alsosubsequently burn up directly adjacent to the outer wall 14 ofvaporizing chamber 2 and maintain the latter at the requiredtemperature, heating unit 5 may be switched off relatively soon. This isdue primarily to the fact that the lower air outlet openings 49 facetoward the outer wall 14 of vaporizing chamber 2 and in a direction sothat the combustion air issuing therefrom hits directly upon the oilvapor issuing from the tangential outlet openings 48, and thusthoroughly intermixes therewith to form a combustible fuel mixture. Theinclination of ribs 25 and the provision of guide plates 51 at an anglevertical to ribs 25, as well as the tangential inclination of outletopenings 48 and 49 insure that the combustion will always occurimmediately adjacent to the outer wall 14 of vaporizing chamber 2.

Although my invention has been illustrated and described with referenceto the preferred embodiments thereof, I wish to have it understood thatit is in no way limited to the details of such embodiments, but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed my invention, what I claim is:

1. An oil burner comprising walls forming a substantially closedvaporizing chamber, means connected to said chamber for feeding oilslowly and gradually into said chamber, a portion of said walls forming,an inner boundary of a combustion chamber adjacent to said vaporizingchamber, said vaporizing chamber having outlet openings at the upperpart thereof leading into said combustion chamber, heating means forheating at least the bottom of said vaporizing chamber to vaporize theoil within said chamber, means within said vaporizing chamber forretarding the flow of oil vapor within said chamber to therebyadditionally heat the vapor therein before passing through said outletopenings into said combustion chamber so as to produce a pressure headwithin said vaporizing chamber, means for conducting air to differentparts of said combustion chamber and for mixing said air with said oilvapor to form a combustible fuel mixture, means within said combustionchamber for igniting said fuel mixture, said vaporizing chamber wallsforming an annular casing surrounded by said combustion chamber andsubstantially coaxial thereto, said outlet openings being disposedadjacent to the outer upper edge of said casing and together forming atleast one ring of openings spaced from each other, said means forconducting air to different parts of said combustion chamber comprisinga cylinder mounted on and coaxial to said annular casing andsubstantially closed at its upper side, the outer diameter of saidcasing being smaller than the diameter of said ring of outlet openings,the side wall of said cylinder being vertically disposed and having aplurality of peripherally equally spaced apertures therein, and aplurality of hollow ribs mounted on and projecting radially outwardlyfrom said cylinder at equal circumferential distances from each other,each of said ribs being disposed over one of said apertures and thuscommunicating with the inside of said cylinder, each of said ribs havingat least two air outlet openings therein above each other and extendingin a tangentially inclined direction with respect to said verticallydisposed side wall through the outer wall of said rib for conducting thecombustion air supplied through said central opening in said casing, andsaid cylinder and said ribs into said combustion chamber.

2. An oil burner as defined in claim 1, further comprising a guide plateon the outer edge of each of said ribs and extending in a substantiallyperipheral direction at least within the area in which said air outletopenings are located.

3. An oil burner as defined in claim 2, wherein the axis of each of saidribs is inclined at an angle of about 20 to 25 to the vertical plane sothat the combustion air emerging from said air outlet openings will atfirst flow obliquely downwardly and then ascend in a spiral directionwithin said combustion chamber.

4. An oil burner as defined in claim 1, wherein the outer wall of saidcasing is provided directly underneath the upper wall thereof withadditional oil-vapor outlet openings, and further comprising a downwardextension on the lower end of each of said ribs, said extensions beingradially spaced from said outer wall of said casing and each havingadditional air outlet openings therein directed toward said outer wallof said casing and at substantially the same level as said additionaloil-vapor outlet opening so that the combustion air emerging from saidlast outlet openings will hit directly upon the oil vapor emerginglaterally from said casing through said additional oil-vapor outletopenings.

5. An oil burner as defined in claim 4, wherein said additional oilvapor outlet openings in the outer wall of said casing and saidadditional air outlet openings in said lower extensions of said ribsextend in tangentially inclined directions with respect to thevertically disposed side wall of the cylinder and are inclined towardeach other so that the combustion of the mixture of oil vapor and airemerging from said outlet openings will occur closely adjacent to saidouter wall of said casing.

6. An oil burner as defined in claim 4, further comprising a guide plateon the outer edge of each of said ribs and extending in a substantiallyperipheral direction from the upper end of said ribs to a point closelyabove said additional air outlet openings, and an additional guide plateon each of said ribs extending at a substantially right angle to saidfirst guide plate and connecting said rib with the adjacent rib at alevel between said air outlet openings in the upper part of said ribsand the additional air outlet openings in said lower extensions of saidribs.

7. An oil burner as defined in claim 6, wherein the axis of each of saidribs and the edges of said guide plates are inclined at an angle ofabout 20 to 25 to the vertical plane so that the combustion air emergingfrom said air outlet openings will at first flow obliquely downwardlyand then ascend in a spiral direction within said combustion chamber,said upper side of said cylinder having a central opening therein, saidair-conducting means further comprising a tube closed at its upper endand mounted on said cylinder within said opening, said tube having aplurality of uniformly distributed air outlet openings within its sidewall and spaced above each other, the lines connecting the correspondingsuperimposed air outlet openings within said tube being likewiseinclined and disposed at an angle of about 10 to 30 to the verticalplane.

8. An oil burner as defined in claim 7, further comprising at least onelaterally projecting wall having a guide surface on said tube at a levelabove said air-outlet openings in said tube for retarding the ascent ofthe combustion gases within said combustion chamber.

9. An oil burner as defined in claim 8, wherein the outer wall of saidtube is provided with at least one additional ring of air outletopenings above said laterally projecting wall having a guide surface.

10. An oil burner as defined in claim 9, further comprising at least oneadditional wall having a guide surface and mounted on the surroundingwall of said combustion chamber and projecting toward said guide surfaceon the wall of said tube but spaced therefrom so as to form aconstricted passage between the free ends of said guide surfaces forretarding the ascent of the combustion gases within said combustionchamber to the level in which said additional ring of air outletopenings is located.

References Cited in the file of this patent UNITED STATES PATENTS1,128,338 McAdams Feb. 16, 1915 1,559,939 Dahl Nov. 3, 1925 1,612,653Rodriguez Dec. 28, 1926 2,458,630 Palko Jan. 11, 1949 2,658,568 BroadyNov. 10, 1953 2,662,589 Aubert Dec. 15, 1953 FOREIGN PATENTS 375,864Great Britain July 4, 1932 163,131 Switzerland Oct. 16, 1933

